28 



LECTURE II. 



From mannose, the monobasic mannonic acid and then the dibasic 

 manno-saccharic acid. 



From galactose the monobasic galactonic acid and then the dibasic 

 mucic acid. 



Fructose behaves quite differently on oxidation. In the case of the 

 above-mentioned sugars, which are all aldoses, acids are obtained by 

 oxidation having the same number of carbon atoms as the original sugars. 

 Fructose, on the other hand, is a ketone, and on being oxidized breaks down 

 into compounds containing a smaller number of carbon atoms. 



These reactions are naturally not peculiar to hexoses, and for the simpler 

 or higher monosaccharides there are corresponding alcohols as well as 

 monobasic and dibasic acids. Thus we have for example: 



Bioses : Alcohol 

 CH 2 OH 



Trioses 



Sugar 



Monobasic Acid Dibasic Acid 



Tetroses 



H 2 OH 

 Glycol 



CH 2 OH 

 CHOH 



CH 2 OH 

 Glycerol 



CH 2 OH 



CHOH 



CHOH 



CH 2 OH 

 d- and l- 

 Erythritol 



CHO CO . OH 



CH 2 OH CH 2 OH 



Glycolose Glycollic Acid 

 (Glycolaldehyde) 



CO. OH 



CHO 



CHOH 



CHoOH 



CO. OH 



CHOH 



CHoOH 



O.OH 

 Oxalic Acid 



CO. OH 



HOH 

 OOH 



Glycerose Glyceric Acids Tartronic Acid 

 (Glyceraldehyde) 



CHO 



CHOH 



CHOH 



CH 2 OH 



d- and l- 

 Erythrose 



CO. OH 



HOH 

 HOH 



H 2 OH 



Erythric 

 Acids 



COOH 

 CHOH 

 CHOH 



COOH 

 Tartaric 

 Acids (4) 



v. 



the algae 



Protococcus 



Erythritol was discovered by Lamy (1852) in 

 vulgaris. It is optically inactive. 



In the group of the pentoses, it has already been stated that arabinose 

 corresponds to the alcohol arabitol and the two acids, arabonic and 1-trioxy- 

 glutaric, while with xylose we have the alcohol xylitol and two correspond- 

 ing acids. Although these last alcohols and acids have up to the present 



